Medium looks very wet for such a small plant in a big pot!
Personally I think it looks like burn from to hot a medium as the leaves are very dark and the new growth has burnt tips too.
Looks like it's growing in soil. If it is you can't really flush soil like coco perlite or a RDWC system.
Just giving it water for a week should see it looking better.
If it's in soil just be careful not to over water it.